Jacob J. Freiberg

Fasting and Nonfasting Lipid Levels Influence of Normal Food Intake on Lipids, Lipoproteins, Apolipoproteins, and Cardiovascular Risk Prediction

Background— Lipid profiles are usually measured after fasting. We tested the hypotheses that these levels change only minimally in response to normal food intake and that nonfasting levels predict cardiovascular events. Methods and Results— We cross-sectionally studied 33 391 individuals 20 to 95 years of age from the Copenhagen General Population Study. We also studied 9319 individuals 20 to 93 years of age from the Copenhagen City Heart Study, 1166 of whom developed cardiovascular events during 14 years of follow-up. Compared with fasting levels, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein (HDL) cholesterol, and albumin levels were reduced up to 3 to 5 hours after the last meal; triglycerides levels were increased up to 6 hours after the last meal; and non-HDL cholesterol level, apolipoprotein A1 level, apolipoprotein B level, ratio of total cholesterol to HDL cholesterol, and ratio of apolipoprotein B to apolipoprotein A1 did not change in response to normal food intake. The maximum changes after normal food and fluid intake from fasting levels were −0.2 mmol/L for total cholesterol, −0.2 mmol/L for low-density lipoprotein cholesterol, −0.1 mmol/L for HDL cholesterol, and 0.3 mmol/L for triglycerides. Highest versus lowest tertile of nonfasting total cholesterol, non-HDL cholesterol, low-density lipoprotein cholesterol, apolipoprotein B, triglycerides, ratio of total cholesterol to HDL cholesterol, and ratio of apolipoprotein B/apolipoprotein A1 and lowest versus highest tertile of nonfasting HDL cholesterol and apolipoprotein A1 predicted 1.7- to 2.4-fold increased risk of cardiovascular events. Conclusions— Lipid profiles at most change minimally in response to normal food intake in individuals in the general population. Furthermore, nonfasting lipid profiles predicted increased risk of cardiovascular events.

Nonfasting Triglycerides and Risk of Ischemic Stroke in the General Population

CONTEXT The role of triglycerides in the risk of ischemic stroke remains controversial. Recently, a strong association was found between elevated levels of nonfasting triglycerides, which indicate the presence of remnant lipoproteins, and increased risk of ischemic heart disease. OBJECTIVE To test the hypothesis that increased levels of nonfasting triglycerides are associated with ischemic stroke in the general population. DESIGN, SETTING, AND PARTICIPANTS The Copenhagen City Heart Study, a prospective, Danish population-based cohort study initiated in 1976, with follow-up through July 2007. Participants were 13,956 men and women aged 20 through 93 years. A cross-sectional study included 9637 individuals attending the 1991-1994 examination of the prospective study. MAIN OUTCOME MEASURES Prospective study: baseline levels of nonfasting triglycerides, other risk factors at baseline and at follow-up examinations, and incidence of ischemic stroke. Cross-sectional study: levels of nonfasting triglycerides, levels of remnant cholesterol, and prevalence of ischemic stroke. RESULTS Of the 13,956 participants in the prospective study, 1529 developed ischemic stroke. Cumulative incidence of ischemic stroke increased with increasing levels of nonfasting triglycerides (log-rank trend, P < .001). Men with elevated nonfasting triglyceride levels of 89 through 176 mg/dL had multivariate-adjusted hazard ratios (HRs) for ischemic stroke of 1.3 (95% CI, 0.8-1.9; 351 events); for 177 through 265 mg/dL, 1.6 (95% CI, 1.0-2.5; 189 events); for 266 through 353 mg/dL, 1.5 (95% CI, 0.9-2.7; 73 events); for 354 through 442 mg/dL, 2.2 (95% CI, 1.1-4.2; 40 events); and for 443 mg/dL or greater, 2.5 (95% CI, 1.3-4.8; 41 events) vs men with nonfasting levels less than 89 mg/dL (HR, 1.0; 85 events) (P < .001 for trend). Corresponding values for women were 1.3 (95% CI, 0.9-1.7; 407 events), 2.0 (95% CI, 1.3-2.9; 135 events), 1.4 (95% CI, 0.7-2.9; 26 events), 2.5 (95% CI, 1.0-6.4; 13 events), and 3.8 (95% CI, 1.3-11; 10 events) vs women with nonfasting triglyceride levels less than 89 mg/dL (HR, 1.0; 159 events) (P < .001 for trend). Absolute 10-year risk of ischemic stroke ranged from 2.6% in men younger than 55 years with nonfasting triglyceride levels of less than 89 mg/dL to 16.7% in men aged 55 years or older with levels of 443 mg/dL or greater. Corresponding values in women were 1.9% and 12.2%. In the cross-sectional study, men with a previous ischemic stroke vs controls had nonfasting triglyceride levels of 191 (IQR, 131-259) mg/dL vs 148 (IQR, 104-214) mg/dL (P < .01); corresponding values for women were 167 (IQR, 121-229) mg/dL vs 127 (IQR, 91-181) mg/dL (P < .05). For remnant cholesterol, corresponding values were 38 (IQR, 26-51) mg/dL vs 29 (IQR, 20-42) mg/dL in men (P < .01) and 33 (IQR, 24-45) mg/dL vs 25 (IQR, 18-35) mg/dL in women (P < .05). CONCLUSION In this study population, nonfasting triglyceride levels were associated with risk of ischemic stroke.

Short Telomere Length, Cancer Survival, and Cancer Risk in 47102 Individuals

BACKGROUND Recent meta-analyses have suggested that short telomere length was associated with increased risk of cancer. We therefore tested the hypotheses that short telomere length was associated with increased risk of cancer and with increased risk of early death after cancer. METHODS We measured leukocyte telomere length in a prospective study of 47 102 Danish general population participants from the Copenhagen City Heart Study and the Copenhagen General Population Study. Participants were followed for up to 20 years for cancer diagnosis and death. Follow-up was 100% complete. All statistical tests were two-sided. RESULTS Telomere length decreased linearly with increasing age (P <.001). During follow-up, we observed 3142 first cancers and, among these individuals, 1730 deaths. Decreasing quartiles of telomere length were associated with decreasing survival after cancer (log-rank P <.001). Multivariable-adjusted hazard ratios of early death were 1.31 (95% confidence interval [CI] = 1.14 to 1.52) in individuals in the quartile and 1.43 (95% CI = 1.13 to 1.80) in individuals in the decile with the shortest telomeres vs the longest. Unadjusted hazard ratios of cancer risk were 1.74 (95% CI = 1.58 to 1.93) and 2.00 (95% CI = 1.70 to 2.35) in individuals in the quartile and decile with the shortest vs longest telomeres; however, multivariable adjustment changed these hazard ratios to 0.98 (95% CI = 0.88 to 1.08) and 0.95 (95% CI = 0.80 to 1.11), mainly because of age adjustment. CONCLUSIONS Short telomere length is associated with reduced survival after cancer but not with cancer risk. The latter contrasts with findings from recent meta-analyses.

Short Telomere Length, Myocardial Infarction, Ischemic Heart Disease, and Early Death

Objective—We tested the hypothesis that short telomere length is associated with increased risk of myocardial infarction, ischemic heart disease, and early death. Methods and Results—We measured leukocyte telomere length in 2 prospective studies of 19 838 Danish general population participants from the Copenhagen City Heart Study and the Copenhagen General Population Study. Participants were followed for up to 19 years for incident myocardial infarction (n=929), ischemic heart disease (n=2038), and death (n=4342). Follow-up was 100% complete. Telomere length decreased linearly with increasing age in women and men in both studies (P=7×10−74 to P=3×10−125). Multifactorially adjusted hazard ratios were 1.10 (95% CI 1.01–1.19) for myocardial infarction, 1.06 (1.00–1.11) for ischemic heart disease, and 1.09 (1.05–1.13) for early death per 1000–base pair decrease in telomere length. The multifactorially adjusted hazard ratios for the shortest versus the longest decile of telomere length were 1.49 (1.07–2.07) for myocardial infarction, 1.24 (1.01–1.53) for ischemic heart disease, and 1.25 (1.07–1.46) for early death. Conclusion—Short telomere length is associated with only modestly increased risk of myocardial infarction, ischemic heart disease, and early death.

Effects of High Thoracic Epidural Analgesia on Myocardial Blood Flow in Patients With Ischemic Heart Disease

Background—In patients with ischemic heart disease, high thoracic epidural analgesia (TEA) has been proposed to improve abnormalities of coronary function by inhibiting cardiac sympathetic tone. We evaluated the effect of TEA on myocardial blood flow in patients with ischemic heart disease. Methods and Results—Twenty male patients with multivessel ischemic heart disease were studied. An epidural catheter was inserted between the second and third thoracic vertebral interspace (Th2 to Th3). Analgesia was induced by epidural injection of bupivacaine 0.5%, and a sensory block from the sixth cervical (C6 to C7) to Th10 (Th8 to Th11) vertebral interspace was achieved. Myocardial blood flow was measured with dynamic 13N-ammonia PET with and without TEA at rest, during pharmacological vasodilation with dipyridamole, and during sympathetic stimulation with the cold pressor test. Myocardial blood flow during dipyridamole increased similarly, regardless of TEA, in all regions except in myocardium subtended by collateral arteries in which blood flow increased more with than without TEA (P<0.05). Without TEA, myocardial blood flow during the cold pressor test remained unchanged compared with myocardial blood flow at rest. In contrast, with TEA, myocardial blood flow increased in all vascular territories. Coronary vascular resistance increased during the cold pressor test without TEA, whereas with TEA, coronary resistance decreased in myocardium subtended by nonstenotic and stenotic coronary vessels and remained unchanged in myocardium subtended by occluded vessels. Conclusions—In patients with multivessel ischemic heart disease, TEA partly normalizes the myocardial blood flow response to sympathetic stimulation.

Plasma 25-hydroxyvitamin D, lung function and risk of chronic obstructive pulmonary disease

Background 25-hydroxyvitamin D (25(OH)D) may be associated with lung function through modulation of pulmonary protease-antiprotease imbalance, airway inflammation, lung remodelling and oxidative stress. We examined the association of plasma 25(OH)D levels with lung function, lung function decline and risk of chronic obstructive pulmonary disease (COPD). Methods Plasma 25(OH)D was measured in 10 116 participants in the Copenhagen City Heart Study and in 8391 participants in the Copenhagen General Population Study. In the former study, up to three measurements of lung function spanning 20 years allowed analyses of lung function decline. Results In both cohorts, forced vital capacity in % of predicted was 7% lower and forced expiratory volume in 1 s in % of predicted was 7–10% lower for lowest versus highest decile of 25(OH)D (ptrend≤1×10−28). In prospective analyses, participants in the lower versus higher 25(OH)D quintiles had a faster decline in forced expiratory volume in 1 s % predicted (pinteraction=1×10−7) and forced vital capacity % predicted (pinteraction=8×10−8). In cross-sectional analyses, multivariable adjusted ORs for COPD were 2.30 (95% CI 1.55 to 3.41) and 3.06 (1.97 to 4.76) for lowest versus highest quintile in the Copenhagen City Heart Study using Global Initiative for Chronic Obstructive Lung Disease (GOLD) and lower limit of normal criteria. The corresponding ORs were 1.82 (1.13 to 2.92) and 2.23 (1.35 to 3.69) in the Copenhagen General Population Study. In prospective analyses, corresponding multivariable adjusted HRs for developing COPD were 1.58 (1.05 to 2.40) and 2.00 (1.19 to 3.36). Conclusions We observed a novel association of lower plasma 25(OH)D levels with faster decline in lung function and with a higher risk of COPD in prospective analyses.

Clinical relevance of non-fasting and postprandial hypertriglyceridemia and remnant cholesterol.

Non-fasting triglycerides are measured at any time within up to 8 h (14 h) after any normal meal, while postprandial triglycerides are measured at a fixed time point within up to 8 h (14 h) of a standardised fat tolerance test. The simplest possible way of evaluating remnant cholesterol is non-fasting/postprandial total cholesterol minus low-density lipoprotein (LDL) cholesterol minus high-density lipoprotein (HDL) cholesterol. Elevated levels of non-fasting/postprandial triglycerides directly correlate with elevated remnant cholesterol. In the general population, 38% of men have non-fasting/postprandial triglycerides > 2mmol/L (>176 mg/dL) while 45% of men have non-fasting/postprandial triglyceride levels of 1-2 mmol/L (89-176 mg/dL); corresponding fractions in women are 20% and 47%. Also, 31% of men have remnant cholesterol levels > 1mmol/L (>39 mg/dL) while 46% of men have remnant cholesterol levels of 0.5-1 mmol/L (19-39 mg/dL); corresponding fractions in women are 15% and 43%. Non-fasting triglycerides ≥5 mmol/L vs. <1 mmol/L marked a 17 and 5 fold increased risk of myocardial infarction, a 5 and 3 fold increased risk of ischemic stroke, and a 4 and 2 fold increased risk of early death in women and men in the general population. As all cells can degrade triglycerides it is biologically unlikely that it is the triglyceride molecules themselves that cause atherosclerosis and cardiovascular disease. However, elevated remnant cholesterol may lead to cholesterol entrapment in the arterial intima and consequently to accelerated atherosclerosis and cardiovascular disease.

Promotor Polymorphisms in Leukotriene C4 Synthase and Risk of Ischemic Cerebrovascular Disease

Objective—Cysteinyl leukotrienes are involved in inflammation and possibly in early carotid atherosclerosis. We tested the hypothesis that the −444 A/C and −1072 G/A polymorphisms of the leukotriene C4 synthase associate with risk of ischemic cerebrovascular disease. Methods and Results—We genotyped 10 592 individuals from the Danish general population, the Copenhagen City Heart Study. During 24 years of follow-up, 557 individuals developed ischemic cerebrovascular disease. The allele frequency was 0.07 for −1072 A and 0.29 for −444 C. Cumulative incidence for ischemic cerebrovascular disease was higher for −1072 AA versus GG genotype (log-rank: P=0.002), and lower for −444 CC versus AA genotype (log-rank: P=0.008). Combined genotypes showed corresponding cumulative incidence differences (log-rank: P=0.003). Multifactorially adjusted hazard ratios for ischemic cerebrovascular disease were 2.8(1.4 to 5.7) for −1072 AA versus GG genotype, 0.6(0.4 to 0.9) for −444 CC versus AA genotype, 2.5(1.2 to 5.4) for combined AA-AA versus GG-AA genotype, and 0.6(0.4 to 0.9) for combined GG-CC versus GG-AA genotype. Genotype did not associate with risk of deep venous thrombosis or severe carotid atherosclerosis, or with levels of platelets and coagulation factors. Conclusions—Leukotriene C4 synthase −1072 AA genotype predict increased risk, whereas −444 CC genotype predict decreased risk of ischemic cerebrovascular disease.

Missense Polymorphisms in BRCA1 and BRCA2 and Risk of Breast and Ovarian Cancer

Purpose: BRCA1 and BRCA2 are key tumor suppressors with a role in cellular DNA repair, genomic stability, and checkpoint control. Mutations in BRCA1 and BRCA2 often cause hereditary breast and ovarian cancer; however, missense polymorphisms in these genes pose a problem in genetic counseling, as their impact on risk of breast and ovarian cancer is unclear. Experimental Design: We resequenced BRCA1 and BRCA2 in 194 women with a familial history of breast and/or ovarian cancer and identified nine possibly biologically relevant polymorphisms (BRCA1 Gln356Arg, Pro871Leu, Glu1038Gly, Ser1613Gly, and Met1652Ile. BRCA2 Asn289His, Asn372His, Asp1420Tyr, and Tyr1915Met). We evaluated risk of breast and/or ovarian cancer by these polymorphisms in a prospective study of 5,743 women from the general population followed for 39 years and in a case-control study of 1,201 breast cancer cases and 4,120 controls. Results: We found no association between heterozygosity or homozygosity for any of the nine polymorphisms and risk of breast and/or ovarian cancer in either study. We had 80% power to exclude hazard/odds ratios for heterozygotes and/or homozygotes for all nine missense polymorphisms above 1.3 to 3.3 in the prospective study, and above 1.2 to 3.2 in the case-control study. Conclusions: Heterozygosity and homozygosity of any of the examined nine BRCA1 and BRCA2 missense polymorphisms cannot explain the increased risk of breast and/or ovarian cancer observed in families with hereditary breast and/or ovarian cancer. Therefore, genetic counseling of such families safely can disregard findings of these missense polymorphisms. (Cancer Epidemiol Biomarkers Prev 2009;18(8):2339–42)

Extreme Nonfasting Remnant Cholesterol vs Extreme LDL Cholesterol as Contributors to Cardiovascular Disease and All-Cause Mortality in 90000 Individuals from the General Population

BACKGROUND Increased nonfasting remnant cholesterol, like increased LDL cholesterol, is causally associated with increased risk for ischemic heart disease (IHD). We tested the hypothesis that extreme concentrations of nonfasting remnant and LDL cholesterol are equal contributors to the risk of IHD, myocardial infarction (MI), and all-cause mortality. METHODS We compared stepwise increasing concentrations of nonfasting remnant and LDL cholesterol for association with risk of IHD, MI, and all-cause mortality in approximately 90 000 individuals from the Danish general population. During up to 22 years of complete follow-up, 4435 participants developed IHD, 1722 developed MI, and 8121 died. RESULTS Compared with participants with nonfasting remnant cholesterol <0.5 mmol/L (19.3 mg/dL), hazard ratios for IHD ranged from 1.3 (95% CI 1.1-1.5) for remnant cholesterol of 0.5-0.99 mmol/L (19.3-38.2 mg/dL) to 2.4 (1.9-2.9) for remnant cholesterol of ≥1.5 mmol/L (58 mg/dL) (P for trend <0.001). Compared with participants with LDL cholesterol <3.0 mmol/L (115.8 mg/dL), hazard ratios for IHD ranged from 1.3 (1.1-1.5) for LDL cholesterol of 3-3.99 mmol/L (115.8-154 mg/dL) to 2.3 (1.9-2.8) for LDL cholesterol of ≥5 mmol/L (193 mg/dL) (P < 0.001). Corresponding hazard ratios for MI ranged from 1.8 (1.4-2.3) to 3.4 (2.5-4.8) for remnant cholesterol (P < 0.001), and from 1.7 (1.4-2.2) to 4.7 (3.5-6.3) for LDL cholesterol (P < 0.001). Nonfasting remnant cholesterol concentrations were associated stepwise with all-cause mortality ranging from hazard ratio 1.0 (0.9-1.1) to 1.6 (1.4-1.9) (P < 0.001), whereas LDL cholesterol concentrations were associated with decreased all-cause mortality risk in a U-shaped pattern, with hazard ratios from 0.8 (0.7-0.8) to 0.9 (0.8-1.0) (P = 0.002). After mutual adjustment, LDL cholesterol best predicted MI, and remnant cholesterol best predicted all-cause mortality. CONCLUSIONS Both lipoproteins were associated equally with risk of IHD and MI; however, only nonfasting remnant cholesterol concentrations were associated stepwise with increased all-cause mortality risk.